'X-Factor' judge Nicole Scherzinger and race car driver Lewis Hamilton failed to zoom their relationship to the finish line as they called it quits, ending their four years of dating.
Being away to each other because of their busy schedules is one of the big reason of their split.
"They'd been long distance for a long time and it's just been hard," a source close to the couple tells PEOPLE.
"They both tried to make it work, but their careers kept them apart. So for now it's over. They think this is what's best. They're definitely going to stay friends."
They first met backstage at the MTV Europe Awards in Munich, Germany in November 2007. Nicole is currently based in LA while Lewis is busy travelling with his racing schedules.
[Photo courtesy by Bauer Griffin]